TECHNICAL TRANSACTIONS CZASOPISMO TECHNICZNE ARCHITECTURE ARCHITEKTURA 7-A/2014 ŁUKASZ WESOŁOWSKI* THE USE OF GLASS CURTAIN WALLS AS PARTITIONS WITH FIRE RESISTANCE IN RESIDENTIAL BUILDINGS – CASE STUDIES STOSOWANIE PRZESZKLONYCH ŚCIAN OSŁONOWYCH JAKO PRZEGRÓD O ODPORNOŚCI OGNIOWEJ W BUDOWNICTWIE MIESZKANIOWYM – WYBRANE ASPEKTY Abstract While analysing the available systems of glass curtain walls one can identify potential problems with their use as partitions with fire resistance. In most cases the metal support structure is made of aluminium. Due to its adhesive and separating interlayer made of plastic materials susceptible to the influence of temperature laminated glass, it does not work well in fire prevention. Manufacturers have products with the required parameters to use in fire partitions and qualified in terms of EI. Currently there are post and transom solutions available on the market which possess a certificate to use the whole system in EI60 fire rating. Internal spaces of posts and transoms in metal support structures are equipped with a filling: a reinforcement made of aluminium. Posts, transoms and thermal strips connecting the clamp strip with a support frame and faying surfaces integrating metal structure are subjected to special protection and safeguarding with thermo-expandable material. Additional protection allows for load-bearing parameters of up to one hour on the weakest link in the system. Producers of glass attest their products in classes from E15 to EI 180, so integrity and fire insulation lies within the aluminium support structure in the whole post and transom glass curtain wall system.The analysis of issues related to the use of glass curtain walls in residential buildings will determine the pattern of wall technology selection to the specific fire prevention requirements. Keywords: fire-rated glass curtain walls, fire protection class of curtain walls, destruction of curtain walls during fire Streszczenie Analizując dostępne na rynku systemy szklanych ścian osłonowych, można zidentyfikować potencjalne problemy stosowania ich jako przegród o odporności pożarowej. Metalowa konstrukcja nośna w większości przypadków wykonana jest z aluminium. Szkło klejone ze względu na warstwy klejące i oddzielające wykonane z tworzyw podatnych na wpływ temperatury źle znosi zastoso- wania z zakresu ppoż. Producenci dysponują produktami posiadającym odpowiednie parametry do zastosowań w przegrodach oddzielenia przeciwpożarowego i kwalifikowane w kategoriach EI. Obecnie na rynku dostępne są rozwiązania słupowo-ryglowe legitymujące się atestem do stosowania całego systemu w parametrach pożarowych EI60. Wewnętrzne przestrzenie słupów i rygli nośnych konstrukcji metalowej wyposażone są we wkładkę – wzmocnienie profilu wykonane z aluminium. Szczególnej ochronie i zabezpieczeniu z materiałem termo-rozszerzalnym poddane są słupy, rygle, listwy termiczne łączące listwę dociskową z profilem nośnym oraz węzły montażowe scalające konstrukcje metalową. Dodatkowa ochrona pozwala na uzyskanie parametrów nośnych rzędu jednej godziny na najsłabszym ogniwie systemu. Producenci szkła atestują swoje produkty w klasach od E15 do EI 180, więc w obrębie całego systemu przeszklonych ścian osłonowych słupowo-ryglowych szczelność i izolacyjność ogniowa leży po stronie aluminiowej konstrukcji nośnej. Analiza problematyki związanej ze stosowaniem przeszklonych ścian osłonowych w budownictwie mieszkaniowym pozwoli określić schemat doboru technologii ściany do konkretnych wymogów pożarowych. Słowa kluczowe: przeszklone ściany osłonowe do zastosowań pożarowych, klasa odporności pożarowej ścian osłonowych, zniszczenie ściany osłonowej podczas pożaru * Ph.D. Eng. Arch. Łukasz Wesołowski, Institute of Structural Design, Faculty of Architecture, Cracow University of Technology. 266 1. Introduction Architectural and building design is sanctioned by legislation to provide uniform requirements of utility with particular emphasis on the use of the best practices to ensure they safet of people, animals and property. The basic regulation, concerning architectural design issues in Poland is the Regulation of the Minister of Infrastructure on the technical conditions to be met by buildings and their location (Dz. U. (Journal of Laws) No. 75, item 690 from 2002 and amended) describing the technical requirements for walls, joints and brittle structures installed at high altitudes. The regulations also apply to the issue of health and safety for users of glass-walled rooms. The modern nature of the partition and its share in the potential energy gains cause more and more frequent presence of such solutions in residential architecture. A glass curtain wall must comply with the relevant mechanical parameters as well as being a safe element, also in terms of fire protection. It is described in the following paragraphs of Technical conditions…: “§216.1 Depending on the height of the building, residential buildings and collective dwellings, are to be erected in fire resistance classes ranging from [A] to [D]. External walls – excluding structural ones – have to ensure tightness (E) and fire insulation (I) from 30 up to 120 minutes. By definition curtain walls do not serve a structural function – i.e., they do not carry the load of the roof, acting only as a barrier to external atmospheric conditions. Three- storey buildings are exempt from fire rating – including single family, farm and individual recreation buildings (§213.1.a), residential-administrative in forestry holdings (§213.1.b) as well as detached two-storey buildings with a capacity of up to 1500 m3 intended for the purpose of tourism and leisure (§213.2.a), with a capacity of up to 1000 m3 with a residential part (§213.2.c)”. Due to the level of technological advancement and significant complexity of glass curtain wall systems, obtaining a certificate of fire rating for the entire set requires the use of additional, costly security. In order to reduce production costs and to popularise solutions, the standard catalogue solutions in this area do not possess fire parameters, as in most applications they tend not to be required by law. 2. Technical solutions in glass curtain walls Due to its adhesive and separating interlayer made of plastic materials susceptible to the influence of temperature, laminated glass does not perform well from the viewpoint of fire prevention. Manufacturers possess products with the required parameters to use in fire partitions and qualified in terms of EI. Fire windows are divided into fire-resistant and fire- retardant categories. Both types of glazing provide protection against heat radiation (defined by “E” parameter of fire rating), while fire-resistant ones serve also as a mechanical barrier to a fire (defined by “EI” parameter of fire rating) [5, 6]. Research on the development of technology of glazing resulted in attempts to fill the interspaces of glazing with a transparent gel-like substance. The gel allows to transfer the heat from the outer to the inner pane of the thermo insulated glazing, thus reducing the temperature and stresses in the glass. Fire-rated glass is about four times more expensive than building glass. Solid laminated glass structures easily exceed 40kg/m2 weight, which causes that the weight of this type of partitions together with the supporting structure, could reach 100 kg/m 2 - 267 a threshold defined as a light structure. The use of a special gel-filled fire glazing can increase the weight of the glazing up to more than 100 kg/m2 (for example, a set of pyro EI120 – 108 kg/m2). Additionally, the profiles of the metal support structure with a fire-rating significantly increase the weight of the glazed system. They must carry a greater load of windows and swelling masses, which thermally secure the internal structural core used in them. While analysing the available systems of glass curtain walls, one can identify potential problems with their use as partitions with fire resistance. In most cases the metal support structure is made of aluminium. A few years ago, due to the shortage of raw materials for the production of aluminium, manufacturers were trying to replace it with a much more accessible steel. Technologically, steel as a less malleable material, was less susceptible to profiling treatment (production of highly complex extruded closed profiles), therefore cold-formed profiles were developed: open and welded ones. The structure’s weight showed a significant increase in comparison with the structures of welded aluminium and cost calculation allowed for slight savings, but the more important aspect was the raw material availability factor. Natural landform has also proven problematic; extruded aluminium profiles had smooth walls of equal thickness and the edges were rounded to a rounding with a very small circular radius. As a result, the structures of this alloy showed a greater predisposition for their use as final finishing elements. Steel rolling in hot profiling has characteristic surfaces of low smoothness. The edges are rounded with radiuses two or three times greater than for aluminium. The corrosiveness of the material was also considered, again with an indication of a lighter alloy. Using steel it was potentially possible to achieve better fire resistance, thanks to a thicker material; however, due to the problematic treatment, the little “technicality” of aesthetics and the problems of degradation of the material, the solution has not gained popularity. Currently there are post and transom solutions available on the market